entry_32.s

linux-2.6.15.6

/*
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas ([e-mail])
 *  Rewritten by Cort Dougan ([e-mail]) for PReP
 *    Copyright (C) 1996 Cort Dougan <[e-mail]>
 *  Adapted for Power Macintosh by Paul Mackerras.
 *  Low-level exception handlers and MMU support
 *  rewritten by Paul Mackerras.
 *    Copyright (C) 1996 Paul Mackerras.
 *  MPC8xx modifications Copyright (C) 1997 Dan Malek ([e-mail]).
 *
 *  This file contains the system call entry code, context switch
 *  code, and exception/interrupt return code for PowerPC.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sys.h>
#include <linux/threads.h>
#include <asm/reg.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/cputable.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/unistd.h>

#undef SHOW_SYSCALLS
#undef SHOW_SYSCALLS_TASK

/*
 * MSR_KERNEL is > 0x10000 on 4xx/Book-E since it include MSR_CE.
 */
#if MSR_KERNEL >= 0x10000
#define LOAD_MSR_KERNEL(r, x)	lis r,(x)@h; ori r,r,(x)@l
#else
#define LOAD_MSR_KERNEL(r, x)	li r,(x)
#endif

#ifdef CONFIG_BOOKE
#include "head_booke.h"
#define TRANSFER_TO_HANDLER_EXC_LEVEL(exc_level)	\
	mtspr	exc_level##_SPRG,r8;			\
	BOOKE_LOAD_EXC_LEVEL_STACK(exc_level);		\
	lwz	r0,GPR10-INT_FRAME_SIZE(r8);		\
	stw	r0,GPR10(r11);				\
	lwz	r0,GPR11-INT_FRAME_SIZE(r8);		\
	stw	r0,GPR11(r11);				\
	mfspr	r8,exc_level##_SPRG

	.globl	mcheck_transfer_to_handler
mcheck_transfer_to_handler:
	TRANSFER_TO_HANDLER_EXC_LEVEL(MCHECK)
	b	transfer_to_handler_full

	.globl	debug_transfer_to_handler
debug_transfer_to_handler:
	TRANSFER_TO_HANDLER_EXC_LEVEL(DEBUG)
	b	transfer_to_handler_full

	.globl	crit_transfer_to_handler
crit_transfer_to_handler:
	TRANSFER_TO_HANDLER_EXC_LEVEL(CRIT)
	/* fall through */
#endif

#ifdef CONFIG_40x
	.globl	crit_transfer_to_handler
crit_transfer_to_handler:
	lwz	r0,crit_r10@l(0)
	stw	r0,GPR10(r11)
	lwz	r0,crit_r11@l(0)
	stw	r0,GPR11(r11)
	/* fall through */
#endif

/*
 * This code finishes saving the registers to the exception frame
 * and jumps to the appropriate handler for the exception, turning
 * on address translation.
 * Note that we rely on the caller having set cr0.eq iff the exception
 * occurred in kernel mode (i.e. MSR:PR = 0).
 */
	.globl	transfer_to_handler_full
transfer_to_handler_full:
	SAVE_NVGPRS(r11)
	/* fall through */

	.globl	transfer_to_handler
transfer_to_handler:
	stw	r2,GPR2(r11)
	stw	r12,_NIP(r11)
	stw	r9,_MSR(r11)
	andi.	r2,r9,MSR_PR
	mfctr	r12
	mfspr	r2,SPRN_XER
	stw	r12,_CTR(r11)
	stw	r2,_XER(r11)
	mfspr	r12,SPRN_SPRG3
	addi	r2,r12,-THREAD
	tovirt(r2,r2)			/* set r2 to current */
	beq	2f			/* if from user, fix up THREAD.regs */
	addi	r11,r1,STACK_FRAME_OVERHEAD
	stw	r11,PT_REGS(r12)
#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
	/* Check to see if the dbcr0 register is set up to debug.  Use the
	   single-step bit to do this. */
	lwz	r12,THREAD_DBCR0(r12)
	andis.	r12,r12,DBCR0_IC@h
	beq+	3f
	/* From user and task is ptraced - load up global dbcr0 */
	li	r12,-1			/* clear all pending debug events */
	mtspr	SPRN_DBSR,r12
	lis	r11,global_dbcr0@ha
	tophys(r11,r11)
	addi	r11,r11,global_dbcr0@l
	lwz	r12,0(r11)
	mtspr	SPRN_DBCR0,r12
	lwz	r12,4(r11)
	addi	r12,r12,-1
	stw	r12,4(r11)
#endif
	b	3f
2:	/* if from kernel, check interrupted DOZE/NAP mode and
         * check for stack overflow
         */
#ifdef CONFIG_6xx
	mfspr	r11,SPRN_HID0
	mtcr	r11
BEGIN_FTR_SECTION
	bt-	8,power_save_6xx_restore	/* Check DOZE */
END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE)
BEGIN_FTR_SECTION
	bt-	9,power_save_6xx_restore	/* Check NAP */
END_FTR_SECTION_IFSET(CPU_FTR_CAN_NAP)
#endif /* CONFIG_6xx */
	.globl transfer_to_handler_cont
transfer_to_handler_cont:
	lwz	r11,THREAD_INFO-THREAD(r12)
	cmplw	r1,r11			/* if r1 <= current->thread_info */
	ble-	stack_ovf		/* then the kernel stack overflowed */
3:
	mflr	r9
	lwz	r11,0(r9)		/* virtual address of handler */
	lwz	r9,4(r9)		/* where to go when done */
	FIX_SRR1(r10,r12)
	mtspr	SPRN_SRR0,r11
	mtspr	SPRN_SRR1,r10
	mtlr	r9
	SYNC
	RFI				/* jump to handler, enable MMU */

/*
 * On kernel stack overflow, load up an initial stack pointer
 * and call StackOverflow(regs), which should not return.
 */
stack_ovf:
	/* sometimes we use a statically-allocated stack, which is OK. */
	lis	r11,_end@h
	ori	r11,r11,_end@l
	cmplw	r1,r11
	ble	3b			/* r1 <= &_end is OK */
	SAVE_NVGPRS(r11)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	lis	r1,init_thread_union@ha
	addi	r1,r1,init_thread_union@l
	addi	r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
	lis	r9,StackOverflow@ha
	addi	r9,r9,StackOverflow@l
	LOAD_MSR_KERNEL(r10,MSR_KERNEL)
	FIX_SRR1(r10,r12)
	mtspr	SPRN_SRR0,r9
	mtspr	SPRN_SRR1,r10
	SYNC
	RFI

/*
 * Handle a system call.
 */
	.stabs	"arch/powerpc/kernel/",N_SO,0,0,0f
	.stabs	"entry_32.S",N_SO,0,0,0f
0:

_GLOBAL(DoSyscall)
	stw	r0,THREAD+LAST_SYSCALL(r2)
	stw	r3,ORIG_GPR3(r1)
	li	r12,0
	stw	r12,RESULT(r1)
	lwz	r11,_CCR(r1)	/* Clear SO bit in CR */
	rlwinm	r11,r11,0,4,2
	stw	r11,_CCR(r1)
#ifdef SHOW_SYSCALLS
	bl	do_show_syscall
#endif /* SHOW_SYSCALLS */
	rlwinm	r10,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
	li	r11,0
	stb	r11,TI_SC_NOERR(r10)
	lwz	r11,TI_FLAGS(r10)
	andi.	r11,r11,_TIF_SYSCALL_T_OR_A
	bne-	syscall_dotrace
syscall_dotrace_cont:
	cmplwi	0,r0,NR_syscalls
	lis	r10,sys_call_table@h
	ori	r10,r10,sys_call_table@l
	slwi	r0,r0,2
	bge-	66f
	lwzx	r10,r10,r0	/* Fetch system call handler [ptr] */
	mtlr	r10
	addi	r9,r1,STACK_FRAME_OVERHEAD
	PPC440EP_ERR42
	blrl			/* Call handler */
	.globl	ret_from_syscall
ret_from_syscall:
#ifdef SHOW_SYSCALLS
	bl	do_show_syscall_exit
#endif
	mr	r6,r3
	li	r11,-_LAST_ERRNO
	cmplw	0,r3,r11
	rlwinm	r12,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
	blt+	30f
	lbz	r11,TI_SC_NOERR(r12)
	cmpwi	r11,0
	bne	30f
	neg	r3,r3
	lwz	r10,_CCR(r1)	/* Set SO bit in CR */
	oris	r10,r10,0x1000
	stw	r10,_CCR(r1)

	/* disable interrupts so current_thread_info()->flags can't change */
30:	LOAD_MSR_KERNEL(r10,MSR_KERNEL)	/* doesn't include MSR_EE */
	SYNC
	MTMSRD(r10)
	lwz	r9,TI_FLAGS(r12)
	andi.	r0,r9,(_TIF_SYSCALL_T_OR_A|_TIF_SIGPENDING|_TIF_NEED_RESCHED)
	bne-	syscall_exit_work
syscall_exit_cont:
#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
	/* If the process has its own DBCR0 value, load it up.  The single
	   step bit tells us that dbcr0 should be loaded. */
	lwz	r0,THREAD+THREAD_DBCR0(r2)
	andis.	r10,r0,DBCR0_IC@h
	bnel-	load_dbcr0
#endif
	stwcx.	r0,0,r1			/* to clear the reservation */
	lwz	r4,_LINK(r1)
	lwz	r5,_CCR(r1)
	mtlr	r4
	mtcr	r5
	lwz	r7,_NIP(r1)
	lwz	r8,_MSR(r1)
	FIX_SRR1(r8, r0)
	lwz	r2,GPR2(r1)
	lwz	r1,GPR1(r1)
	mtspr	SPRN_SRR0,r7
	mtspr	SPRN_SRR1,r8
	SYNC
	RFI

66:	li	r3,-ENOSYS
	b	ret_from_syscall

	.globl	ret_from_fork
ret_from_fork:
	REST_NVGPRS(r1)
	bl	schedule_tail
	li	r3,0
	b	ret_from_syscall

/* Traced system call support */
syscall_dotrace:
	SAVE_NVGPRS(r1)
	li	r0,0xc00
	stw	r0,_TRAP(r1)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_syscall_trace_enter
	lwz	r0,GPR0(r1)	/* Restore original registers */
	lwz	r3,GPR3(r1)
	lwz	r4,GPR4(r1)
	lwz	r5,GPR5(r1)
	lwz	r6,GPR6(r1)
	lwz	r7,GPR7(r1)
	lwz	r8,GPR8(r1)
	REST_NVGPRS(r1)
	b	syscall_dotrace_cont

syscall_exit_work:
	stw	r6,RESULT(r1)	/* Save result */
	stw	r3,GPR3(r1)	/* Update return value */
	andi.	r0,r9,_TIF_SYSCALL_T_OR_A
	beq	5f
	ori	r10,r10,MSR_EE
	SYNC
	MTMSRD(r10)		/* re-enable interrupts */
	lwz	r4,_TRAP(r1)
	andi.	r4,r4,1
	beq	4f
	SAVE_NVGPRS(r1)
	li	r4,0xc00
	stw	r4,_TRAP(r1)
4:
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_syscall_trace_leave
	REST_NVGPRS(r1)
2:
	lwz	r3,GPR3(r1)
	LOAD_MSR_KERNEL(r10,MSR_KERNEL)	/* doesn't include MSR_EE */
	SYNC
	MTMSRD(r10)		/* disable interrupts again */
	rlwinm	r12,r1,0,0,(31-THREAD_SHIFT)	/* current_thread_info() */
	lwz	r9,TI_FLAGS(r12)
5:
	andi.	r0,r9,_TIF_NEED_RESCHED
	bne	1f
	lwz	r5,_MSR(r1)
	andi.	r5,r5,MSR_PR
	beq	syscall_exit_cont
	andi.	r0,r9,_TIF_SIGPENDING
	beq	syscall_exit_cont
	b	do_user_signal
1:
	ori	r10,r10,MSR_EE
	SYNC
	MTMSRD(r10)		/* re-enable interrupts */
	bl	schedule
	b	2b

#ifdef SHOW_SYSCALLS
do_show_syscall:
#ifdef SHOW_SYSCALLS_TASK
	lis	r11,show_syscalls_task@ha
	lwz	r11,show_syscalls_task@l(r11)
	cmp	0,r2,r11
	bnelr
#endif
	stw	r31,GPR31(r1)
	mflr	r31
	lis	r3,7f@ha
	addi	r3,r3,7f@l
	lwz	r4,GPR0(r1)
	lwz	r5,GPR3(r1)
	lwz	r6,GPR4(r1)
	lwz	r7,GPR5(r1)
	lwz	r8,GPR6(r1)
	lwz	r9,GPR7(r1)
	bl	printk
	lis	r3,77f@ha
	addi	r3,r3,77f@l
	lwz	r4,GPR8(r1)
	mr	r5,r2
	bl	printk
	lwz	r0,GPR0(r1)
	lwz	r3,GPR3(r1)
	lwz	r4,GPR4(r1)
	lwz	r5,GPR5(r1)
	lwz	r6,GPR6(r1)
	lwz	r7,GPR7(r1)
	lwz	r8,GPR8(r1)
	mtlr	r31
	lwz	r31,GPR31(r1)
	blr

do_show_syscall_exit:
#ifdef SHOW_SYSCALLS_TASK
	lis	r11,show_syscalls_task@ha
	lwz	r11,show_syscalls_task@l(r11)
	cmp	0,r2,r11
	bnelr
#endif
	stw	r31,GPR31(r1)
	mflr	r31
	stw	r3,RESULT(r1)	/* Save result */
	mr	r4,r3
	lis	r3,79f@ha
	addi	r3,r3,79f@l
	bl	printk
	lwz	r3,RESULT(r1)
	mtlr	r31
	lwz	r31,GPR31(r1)
	blr

7:	.string	"syscall %d(%x, %x, %x, %x, %x, "
77:	.string	"%x), current=%p\n"
79:	.string	" -> %x\n"
	.align	2,0

#ifdef SHOW_SYSCALLS_TASK
	.data
	.globl	show_syscalls_task
show_syscalls_task:
	.long	-1
	.text
#endif
#endif /* SHOW_SYSCALLS */

/*
 * The sigsuspend and rt_sigsuspend system calls can call do_signal
 * and thus put the process into the stopped state where we might
 * want to examine its user state with ptrace.  Therefore we need
 * to save all the nonvolatile registers (r13 - r31) before calling
 * the C code.
 */
	.globl	ppc_sigsuspend
ppc_sigsuspend:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_sigsuspend

	.globl	ppc_rt_sigsuspend
ppc_rt_sigsuspend:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30
	stw	r0,_TRAP(r1)
	b	sys_rt_sigsuspend

	.globl	ppc_fork
ppc_fork:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_fork

	.globl	ppc_vfork
ppc_vfork:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_vfork

	.globl	ppc_clone
ppc_clone:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_clone

	.globl	ppc_swapcontext
ppc_swapcontext:
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	rlwinm	r0,r0,0,0,30		/* clear LSB to indicate full */
	stw	r0,_TRAP(r1)		/* register set saved */
	b	sys_swapcontext

/*
 * Top-level page fault handling.
 * This is in assembler because if do_page_fault tells us that
 * it is a bad kernel page fault, we want to save the non-volatile
 * registers before calling bad_page_fault.
 */
	.globl	handle_page_fault
handle_page_fault:
	stw	r4,_DAR(r1)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	bl	do_page_fault
	cmpwi	r3,0
	beq+	ret_from_except
	SAVE_NVGPRS(r1)
	lwz	r0,_TRAP(r1)
	clrrwi	r0,r0,1
	stw	r0,_TRAP(r1)
	mr	r5,r3
	addi	r3,r1,STACK_FRAME_OVERHEAD
	lwz	r4,_DAR(r1)
	bl	bad_page_fault
	b	ret_from_except_full

/*
 * This routine switches between two different tasks.  The process
 * state of one is saved on its kernel stack.  Then the state
 * of the other is restored from its kernel stack.  The memory
 * management hardware is updated to the second process's state.
 * Finally, we can return to the second process.
 * On entry, r3 points to the THREAD for the current task, r4
 * points to the THREAD for the new task.
 *
 * This routine is always called with interrupts disabled.
 *
 * Note: there are two ways to get to the "going out" portion
 * of this code; either by coming in via the entry (_switch)
 * or via "fork" which must set up an environment equivalent
 * to the "_switch" path.  If you change this , you'll have to
 * change the fork code also.
 *
 * The code which creates the new task context is in 'copy_thread'
 * in arch/ppc/kernel/process.c
 */
_GLOBAL(_switch)